doc/getting_started: mention ZEPHYR_TOOLCHAIN_VARIANT=llvm

Mention that host installed clang can be used for native_posix.

Signed-off-by: Oleg Zhurakivskyy <[email protected]>

Author: ozhuraki

doc/getting_started/index.rst

@@ -156,7 +156,8 @@ Set Up a Toolchain
    In some specific configurations like non-MCU x86 targets on Linux,
    you may be able to re-use the native development tools provided by
    your operating system instead of an SDK by setting
-   ``ZEPHYR_TOOLCHAIN_VARIANT=host``.
+   ``ZEPHYR_TOOLCHAIN_VARIANT=host`` for gcc or
+   ``ZEPHYR_TOOLCHAIN_VARIANT=llvm`` for clang.
 
    If you want, you can use the SDK host tools (such as OpenOCD) with a
    different toolchain by keeping the :envvar:`ZEPHYR_SDK_INSTALL_DIR`